The field of invention relates generally to safety devices, and more particularly, pertains to a safety shut-off device, or dead-man switch, for gas welding apparatus.
A well known problem in the gas welding industry is that the technology for gas welding apparatus has not been evolving as quickly as that of other industrial devices. This is especially unfortunate in light of the inherent danger in the use of cutting and welding equipment such as that which uses a combination of either oxygen and acetylene or oxygen and propane. The danger is at such a level that some service stations are denied the use of the apparatus because of insurance rules. The danger inherent in applying a flame to the grease laden under-carriage of a motor vehicle is apparent. Also, there are often combustibles, such as rags, in the vicinity of the work area. The danger even exists for the standard plumber's pony torch which operates on air and acetylene.
One attempt to improve the safety of gas welding apparatus involves the use of fire extinguishers at the work area. Relying solely on the user of the gas welding apparatus to utilize the fire extinguisher has proved impractical. For example, the user must turn off the gas welding apparatus, set down the torch handle, locate the fire extinguisher, which is often some distance from the location of the mishap, and return to the location to begin the extinguishing process. Attempts to have a second person standing by with an extinguisher have not proved practical.
Some attempts have been made to equip gas welding apparatus with complex and bulky devices for cutting off the combustion reagents and for beginning the flow of an extinguishing gas through the apparatus. However, such devices have required a positive action to accomplish the desired result.
There has been no provision for a true "deadman" switch for gas welding apparatus, or a pony torch, where a positive action is required to permit the torch to burn, and where the release of the apparatus will cause the flame to extinguish.
A further problem has been that any safety devices available for gas welding apparatus have required the purchase of new equipment with the safety device. In other words, there has been no provision for retrofitting existing gas welding apparatus with safety devices.
These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, a principal object of the invention to provide a novel safety shut-off device for gas welding apparatus that will provide a true dead-man switch, whereby the positive action of grasping a trigger member is required for the apparatus to operate.
Another object of this invention is the provision of such a safety shut-off device that can be retro-fitted to existing gas welding apparatus.
A further object of the present invention is the provision of such a safety shut-off device in which the trigger actuating the apparatus is dimensioned and configured to be grasped by two hands at once, allowing the user to change hands without releasing the trigger of the safety shut-off device.
It is another object of the instant invention to provide such a safety shut-off device in which the user will not have to readjust the mixture of gasses in the gas welding apparatus to re-light the apparatus after the safety shut-off device extinguishes the flame of the apparatus.
A still further object of the invention is the provision of a such a safety shut-off device which is simple in construction, inexpensive to manufacture, and which is capable of a long life of useful service with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.